Electrical control device



Aug. 30, 1932. J KR E 1,874,548

ELECTRICAL CONTROL DEVICE Filed NOV. 27. 1929 2 Sheets-Sheet 1IIIIIIIIIIlIIIII/IIII/III/III//lI////II/II/II/II/l I VENTOR +5 ATTORNEYAug. 30, 1932. KREMER 1,874,548

ELECTRICAL CONTROL DEVICE Filed Nov. 27, 1929 2 Sheets-Sheet 2 ATTORNEYPatented Aug. 30, 1932 IUNITEDNSTATES iPA-TENT OFFICE JOHN KREMER, OFWEST ORANGE, NEW JERSEY, ASSIGNOR TO CHARLES ENGELHARD,

1110., OF N NEW JERSEY CORPORATION OF NEW JERSEY I ELECTRICAL CONTROLDEVICE Application filed November 27, 1929. Serial No. 410,066.

This invention relates to electrical control devices, and moreparticularly to automatic control and indicating instruments adapted foruse in connection with heat generating appointer in turn closing theswitch, the latter being so positioned that the pointer will beeffective only when a maximum condition has been attained.

Obviously, in order to insure proper operation and prevent actuation ofthe opening and closing switches at an improper time, that is, beforethe maximum has been reached, it is necessary that the depressor bar beaccurately adjusted; in many instances,

these adjustments being in the neighborhood of .002 of an inch.

It is an object of this invention to provide an arrangement of switchesin a control instrument by which the circuit closing switch isperiodically actuated independently of the movements of the depressorbar.

A further object is the provision of a control device in which a circuitopening switch is actuated for a predetermined time before and after theactuation of circuit closing switch when a maximum condition has beenreached.

These and other objects are attained by the novel construction,combination and arrangement of parts hereinafter described and shown inthe accompanying drawings, constituting a material part of thisdisclosure and in which:

Figure 1 represents an elevational View of an indicating instrumentembodying the invention.

. springs 21.

bent portion 26 carrying a roller 27, the latsprings 35 and 38 beingattached to and sep- Figure 2 is a bottom View ofthe instrument shown inFigure 1.

Figure 3 represents a sectional view taken on the line 33 of Figure 2.

Figure 4 represents an inverted side View of a section of theinstrument.

Figure 5 represents a diagram illustrating the relative-periods ofclosing of switches employed in the instrument.

Referring to Figure 2, the instrument is shown to include a main frame6, upon which is supported a horse shoe magnet 7, of a galvanometer. Theframe has attached theretoan arcuate cross-bar 8, which supports a scale9. The instrument is carried in a casing 10, having a detachable cover11, the latter being provided with a glass window 12 to enable the scaleto be visible.

Rotatably mounted on a shaft 13 depending from the frame 6, is an arm14, supporting a vertical bar 15, upon which is carried a horizontalshelf 16, having mounted thereon a pair of contacts 17 and 18, Figure 1,adapted to be engaged by contacts 17 and 18' attached to plates 19 and20, respectively, said plates being supported by the shelf 16, andnormally helcgfiln an e)levated position by leaf A pointer 22, connectedwith the movable element of the galvanometer, traverses the scale 9, andhas attached thereto a lug 22' for the purpose hereinafter described.

A substantially U-shaped depressor bar 23 is positioned above thepointer and the plates 19 and 20, the depressor bar being piv otallymounted to the frame 6 at 24, Fig. 4, and is normally urged downward bya tension spring 25.

One leg of the bar 23 has a downwardly ter engaging the cam surface 28of a disc 29 fixed to a shaft 30 which is connected to a small electricmotor 32, Figures 1 and 2, having a predetermined speed.

Also fixed to shaft 30 is a disc 33 having a peripheral lug 34 adaptedto periodically engage the leaf spring 35 upon which is carried acontact 36 adapted to engage a similar contact 37 carried by a leafspring 38, the

furnace. At the same" time, the rotation of disc 29 causes the depressorbar 23 to be inter mittently raised and lowered.

As the heat in the furnace increases, the galvanometer is affected andneedle 22 traverses the scale 9 until it is above either plate 19 0r'20,at which position depressor bar 23 bears down on the needle, and the lug22 on the needle bears down on the plate to cause contacts 17 and 17 orcontacts 18 and 18 to be engaged to close a c1rcu1t through appara-' tusdesigned to continue'or discontinue the generation of heat in thefurnace.

Cam 28 is so'designed and positioned relative to lug 34 that the flow ofheat will be discontinued 18 before the contacts 36 and 37 are broughtintoengagement and 18 afterwards. r

'The contacts 36 and 37 remain engaged for a period of 12, so that thecam 28 embraces an arc of 48, the apparatus for discontinuing the flowof heat being in operation throughout that period. This arrangementeliminates the possibility of faulty operation of the controlinstrument, and as soon as the furnace heat has decreased to an' extentsuffie'ient to cause the pointer to clear the plates 19 and 20, the heatgenerating apparatus will again be placed in operation by the engagementof contacts 36 and 87.

The switch control arrangement herein described necessitates theactuation of only one switch by the pointerand the depressor bar;

and since the heat generating switch is 'en-.

I claim as new and desire to secure by Letters Patent is:

In a control instrument, a shaft, means. for rotating the shaft at apredetermined speed, a pair of leaf springs attached to and separated bya block of insulating material, said leaf springscarrying contacts, saidcontacts being normally spaced apart, a disc fixed to the shaft andhaving a peripheral lug periodlcally engageable with one of the leafsprings to force the contacts into engagement, I

a depressor bar pivotally supported interme diate of its ends, saiddepressor bar having a downturned portion; at one side of the pivot anda transverse portion at the opposite side of the pivot, a cam disc fixedto the shaft adjacent the first mentioned disc and engaging thedownturned portion of the depressor bar to intermittently actuate thelatter, a normally open switch positioned beneath thetransverse portionof the depressorbar, and a meter pointer movable above said switch andcooperating with the depressor bar to close the switch when the pointeris in a predetermlned position, said cam disc being so shaped andarranged'relative to the first ment oned disc as to-maintaln thedepressor bar depressed for a definite time before and aftertheengagement and disengagement of the contacts on-theleaf springs.

This specification signed this 22nd day of November, 1929. V V j 7, JOHNKREMER.

. tirely independent of the pointer or the po- V sition of the pointer,or the setting of the cut-off switches, it may be made mechanicallystronger than has heretofore been possible.

This feature is of great advantage, espe- V 6 cially in view of the factthat in depressor bar actuated switches very close adjustment of thedepressor bar is necessary, such adjustmentsin many instances being inthe neighand a cut-ofi switch simultaneously at an improper time.

borhood of .002 of an inch, in order to avoid making contact with a heatgenerating switch The foregoing d sclosure is tobe regarded asdescriptive and illustrative only, and not as restrictive or limitativeof the invention, of

. which, obviously, an embodiment may be con structed includingmodifications Without departing from the general scope herein indicatedand denoted in the appended claim.

, Having thus 'describedmy invention what

